D.C. United displayed the kind of defensive dominance yesterday that made it the best team in MLS in the regular season.

But it didn’t matter.

United players were left dumbfounded and motionless on the RFK Stadium grass after a 1-0 loss in the Eastern Conference final. New England scored on its only shot on goal when reigning league MVP and former Maryland star Taylor Twellman converted in the fourth minute.

United kept up a relentless attack — taking eight shots on goal and 18 shots overall — but could not get one past star goalkeeper Matt Reis.

“It’s a cruel irony,” United midfielder Ben Olsen said. “We have been waiting for this performance for a long time. And it didn’t help us.”

Olsen took the last shot from left side, but it went just outside the right goal post seconds before injury time expired. The Revolution celebrated and moved on to Sunday’s MLS Cup, where they will play for the franchise’s first title against the Houston Dynamo, who defeated the Colorado Rapids 3-1 last night.

And United saw its wacky season and championship aspirations end in fruitless fashion in front of a shocked crowd of 19,552. A sign in New England’s cheering section in the second deck read: “IT IS OUR TIME.”

“We all know we played one of the best games we have in a very long time. It was a great effort,” said United coach Peter Nowak, who did not answer the question of whether he expects to be back next season. “It just wasn’t meant to be. So many chances. We just didn’t get a goal.”

The Revolution had the only shot they would need in the fourth minute. Twellman one-timed a bouncing ball from 14 yards out to beat goalkeeper Troy Perkins. Midfielder Jay Heaps started the play by passing to Pat Noonan just outside the penalty box on the right side. Noonan sent a cross toward the goal, and Twellman quickly delivered from in front of the goal.

“We always say we have to prevent the service from the wings,” Novak said. “I think Bobby [Boswell] went for the double team, and the ball was in the air a lot. It was a great strike, their only shot on goal.”

New England packed it in and played defense after that. Even though United continually peppered the goal area, the defense, particularly Reis (eight saves), was able to protect the early lead.

“We allowed a team to score an early goal and sit back and defend,” said United forward Alecko Eskandarian, who left the game in the 75th minute with cramps in his calves. “[Reis] is a big part of their defense. I don’t think it was as much them as it was us. An extra pass here, an extra play here, an extra touch and it’s an easy goal for us. We kind of killed ourselves.”

Eskandarian was one of several United stars who finished the season on the bench. Freddy Adu, who was effective particularly in the first half and had two shots on goal, was replaced in the 65th minute by Matias Donnet for matchup reasons. Christian Gomez, a candidate for league MVP who scored both United goals in the first-round playoff series win over New York, apparently left with cramps in the 81st minute.

Adu, 17, took the substitution hard and immediately put his head in his hands on the bench, which may be the last image of him playing for United. He said there are “serious talks” about him playing overseas next season.

“It wasn’t a great feeling coming out of the game, but coaches have what they want to do in mind. And you have to respect it and honor it. I did,” said Adu, who has criticized Novak about his playing time in past seasons. “We made one mistake out there the whole game and lost on that. One mistake. It hurts. The way it ended, just watching the game from the bench the last [25] minutes was probably the worst feeling I had my whole life. It’s a horrible feeling.”

United still had hope until Olsen missed the final shot. The midfielder nearly tied the game moments earlier when he narrowly missed getting his head on the ball deep in the box as Reis made a leaping grab. The goalkeeper also stopped Olsen’s twisting header from 15 yards out late in the game.

“It’s killing me to even talk about,” Olsen said. “I feel like I left a goal out there.”